CB-001558
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Glycosaminoglycans in Urine
Specimen Type
Urine
Specimen
Volume
20 mL
Collection
Urine collection cup. Freeze immediately. Include the patient age with the requisition.
Minimum
Volume
10 mL
Handling
Ship frozen on dry ice.
Rejection
Criteria
Unfrozen specimens.
Stability
3 freeze-thaw cycles.
Specimens outside of listed stability.
o
Frozen at -20 C for 8 weeks.
o
Frozen at -80 C for 8 weeks.
Methodology
Reference
Range
Turnaround
Time
CPT Code
Colorimetric (1,9-dimethyl-methylene blue) dye binding
0-1 year
< 36.0 mg gags/mmol creatinine
2-3 years
< 15.0 mg gags/mmol creatinine
4-5 years
< 10.5 mg gags/mmol creatinine
6-7 years
< 10.3 mg gags/mmol creatinine
8-9 years
< 9.6 mg gags/mmol creatinine
10-11 years
< 8.2 mg gags/mmol creatinine
12-13 years
< 6.4 mg gags/mmol creatinine
>13years
< 5.5 mg gags/mmol creatinine
Up to 7 business days.
83864
Cambridge Biomedical Inc. • 1320 Soldiers Field Road Boston, MA 02135 • Customer Service T: 617.456.0800 F: 617.456.0801
www.cambridgebiomedical.com
CB-001558
Page 2 of 2
Glycosaminoglycans in Urine
Clinical
Significance
The mucopolysaccharidoses (MPSs) are a family of inheritable disorders caused by a deficiency of lysomal
enzymes required to degrade mucopolysaccharides, also known as glycosaminoglycans (GAGs). The undegraded or partially degraded GAGs are stored in lysosomes and excreted in the urine. The quantity of
excreted urinary GAGs is age-dependent. Infants secrete more GAGs than adults. Normal urine contains
primarily chondroitin sulfate with small quantities of heparin sulfate and dermatan sulfate.
Once mucopolysaccharidoses is diagnosed by total GAG analysis, a differential diagnosis based upon the
abnormal distribution of sulfated GAGs in urine must be performed. Differential diagnosis is a requirement
because many of the various enzyme deficiencies share similar clinical features. These features include a
chronic and progressive course, multi-system involvement and organomegaly. Hearing, vision, cardiovascular
function and joint mobility are affected. Profound mental retardation is found in the Hurler, Hunter and San
Filippo syndromes (MPS types I, II and III), but normal intellectual functioning is retained in other MPSs and
some mildly affected Hunter patients.
Principle
The urine samples are pre-treated to concentrate the glycosaminoglycans and remove any background,
interfering components. The samples, controls and standards are incubated with a dye label (1,9-dimethylmethylene blue). The dye binds specifically with the sulfated, polysaccharide component of proteoglycans and
protein-free, sulfated, glycosaminoglycan chains. The dye-GAG complexes precipitate within 10 minutes. The
samples, controls and standards are centrifuged and the supernatant decanted. The samples are re-dissolved in
a disassociation reagent. After an incubation step, the absorbance of the samples are measured at 656nm. The
absorbance of the samples are compared to known standards and the concentrations of the samples are
determined.
Finally, the GAG concentration is normalized against creatinine in order to control for variation in urine flow
rates.
Cambridge Biomedical Inc. • 1320 Soldiers Field Road Boston, MA 02135 • Customer Service T: 617.456.0800 F: 617.456.0801
www.cambridgebiomedical.com